I recognise so much of what you say about hanging onto this marriage even though it wasn't good. When I wrote down what I was hanging onto; shared history, financial security; 30 years etc etc; none of these things were about him. Irrespective of his abominal behaviour to you; neither of you should actually feel obliged to stay in an unhealthy relationship.
It's dead; it's gone. You are grieving, but you have to acknowledge the marriage has died, bury it and move on in your emotions.
You can torment yourself with 'what ifs' and 'whys' but it doesn't matter. Accept what is happening today, not what went before.
I have internal dialogues and whenever I feel the 'what ifs' coming on, I remind myself that he wasn't that person after all, because he lied, cheated and manipulated.
Write a list of what a future partner would look like; what qualities would you look for, what are your non negotiables? Mine were honesty, fidelity and selflessness. Does he tick those boxes? No. So until he does, he doesn't deserve my time. Will he ever? I don't know, but that's down to him.
I imagine all the nasty stuff coming out of his mouth is because he senses he is losing control and is panicking. Therefore this is actually in your control.
He needs to show massive changes; until he does you need to stop giving him the time of day. You don't not need this man in your life abusing you. That is your choice and your control. Only when he shows massive change do you even contemplate whether to allow him back into your life. That is in your control.
I sometimes wonder what would have happened if he'd had the decency 3 years ago to sit down and discuss the marriage; would it have survived? But he didn't and the fact that he made decisions to carry on as normal, carry on a 16 month affair, lie and manipulate, move out, come back etc etc make it a pointless exercise. But it does demonstrate to me a lack of respect,lack of basic decency and that he is a coward who could only think of his own immediate needs. I always told him that I could try to forgive the affair and that people make mistakes but it is how they rectify them and behave after that truly matters. If I judge him by his behaviour post BD then it is that which shows why I won't entertain him at the moment.
Do you still have a chance? Yes, but you cannot continue like this. Wait and see if he can make the necessary effort to change and treat you respectfully and in the meanwhile work on your fears by broadening your life with what makes you tick. You may well find that you don't want him back but that only comes from burying that relationship, lifting your head up high and saying 'right, what do I want'
You can do it. NOBODY needs somebody else to feel alive and worthwhile. You are alive and worthwhile and obviously an amazing and strong person. Look what he's put you through and you are still standing. Keep getting stronger. He will either accept the loss of control or he'll fight against it. But you are stronger than him because you are a decent, loving person. Show that strength. It may just be what wakes him up to realise what an a*** he is being.
Forgive my bluntness. I'm from the North of England and it's a well known trait!